Multi-stage transmission for vehicle

ABSTRACT

A multi-stage transmission for a vehicle is provided that has at least nine forward shifting stages and one reverse shifting stage with a relatively small number of parts and a configuration such that an engine may be operated at desired operation points, thereby increasing fuel efficiency of the vehicle, and the engine may be operated more quietly, thereby improving the quietness of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of non-provision U.S.patent application Ser. No. 14/884,562, filed on Oct. 15, 2015, whichclaims priority to and the benefit of Korean Patent Application No.10-2015-0034772, filed on Mar. 13, 2015, the entirety of each of whichare hereby incorporated by reference.

FIELD

The present disclosure generally relates to a multi-stage transmissionfor a vehicle.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Recent rising oil prices have driven worldwide car manufacturers intounlimited competition to improve fuel efficiency. In addition, greatefforts have been made to reduce the weight and improve the fuelefficiency of engines based on a variety of techniques such asdownsizing, and similar measures.

Meanwhile, among methods utilized for transmissions equipped in vehiclesto improve fuel efficiency, there is a method allowing an engine tooperate at more efficient operation points using the multi-staging of atransmission, thereby improving the fuel efficiency.

Further, such the multi-staging of a transmission allows an engine tooperate in a relatively low RPM (revolutions per minute) range.

However, as the number of shifting stages of a transmission increases,the number of internal parts constituting the transmission alsoincreases. This may lead to undesirable effects instead, such as thereduced mountability and transfer efficiency and the increased cost andweight of the transmission

SUMMARY

The present disclosure provides a multi-stage transmission for a vehiclethat has at least nine forward shifting stages and one reverse shiftingstage with a relatively small number of parts and a simple configurationsuch that an engine may be operated at desired operation points, therebyproviding an improvement in the fuel efficiency of the vehicle, and theengine may be operated more quietly, thereby improving the quietness ofthe vehicle.

According to one form of the present disclosure, there is provided amulti-stage transmission for a vehicle including: an input shaft; anoutput shaft; a first to fourth planetary gear devices disposed betweenthe input shaft and the output shaft to transmit rotary force. Each ofthe first to fourth planetary gear devices has three rotary elements,and at least six shifting elements connected to the rotary elements ofthe planetary gear devices. A first rotary element of the firstplanetary gear device may be installed to be fixed, a second rotaryelement of the first planetary gear device may stay connected to a thirdrotary element of the second planetary gear device, and a third rotaryelement of the first planetary gear device may be variably connected toa second rotary element of the second planetary gear device and staysconnected to a first rotary element of the third planetary gear deviceand a first rotary element of the fourth planetary gear device. A firstrotary element of the second planetary gear device may be variablyconnected to the input shaft, and the second rotary element of thesecond planetary gear device may be installed to be selectively fixableby one shifting element of the at least six shifting elements andvariably connected to the input shaft. A second rotary element of thethird planetary gear device may stay connected to the output shaft, anda third rotary element of the third planetary gear device may beinstalled to be selectively fixable by another of the at least sixshifting elements. A second rotary element of the fourth planetary geardevice may be configured to be selectively connected to the input shaft,and a third rotary element of the fourth planetary gear device may beconfigured to secure a state at least even temporarily connected to theoutput shaft.

According to another aspect of the present disclosure, the multi-stagetransmission includes a first to fourth planetary gear devices havingthree rotary elements, respectively; six shifting elements configured tovariably provide frictional force; and a first to eighth rotary shaftsconnected to the rotary elements of the first to fourth planetary geardevices. The first rotary shaft may be an input shaft. The second rotaryshaft may be directly connected to a second rotary element of the secondplanetary gear device. The third rotary shaft may be directly connectedto a second rotary element of the first planetary gear device and athird rotary element of the second planetary gear device. The fourthrotary shaft may be directly connected to a third rotary element of thefirst planetary gear device, a first rotary element of the thirdplanetary gear device and a first rotary element of the fourth planetarygear device. The fifth rotary shaft may be directly connected to a firstrotary element of the second planetary gear device. The sixth rotaryshaft may be directly connected to a third rotary element of the thirdplanetary gear device. The seventh rotary shaft may be a second rotaryelement of the fourth planetary gear device. And the eighth rotary shaftmay be an output shaft directly connected to a second rotary element ofthe third planetary gear device and a third rotary element of the fourthplanetary gear device. The six shifting elements may include first tofourth clutches and first and second brakes. The first clutch may bedisposed between the first rotary shaft and the second rotary shaft. Thesecond clutch may be disposed between the second rotary shaft and thefourth rotary shaft. The third clutch may be disposed between the firstrotary shaft and the fifth rotary shaft. The fourth clutch may bedisposed between the first rotary shaft and the seventh rotary shaft.The first brake may be disposed between the second rotary shaft and atransmission case, and the second brake may be disposed between thesixth rotary shaft and the transmission case.

According to still another aspect of the present disclosure, is amulti-stage transmission for a vehicle including a first to fourthplanetary gear devices having three rotary elements, respectively. Sixshifting elements configured to variably provide frictional force, and afirst to eighth rotary shafts connected to the rotary elements of thefirst to fourth planetary gear devices. The first rotary shaft may be aninput shaft. The second rotary shaft may be directly connected to asecond rotary element of the second planetary gear device. The thirdrotary shaft may be directly connected to a second rotary element of thefirst planetary gear device and a third rotary element of the secondplanetary gear device. The fourth rotary shaft may be directly connectedto a third rotary element of the first planetary gear device, a firstrotary element of the third planetary gear device and a first rotaryelement of the fourth planetary gear device. The fifth rotary shaft maybe directly connected to a first rotary element of the second planetarygear device. The sixth rotary shaft may be directly connected to a thirdrotary element of the third planetary gear device. The seventh rotaryshaft may be directly connected to a third rotary element of the fourthplanetary gear device. The eighth rotary shaft may be an output shaftdirectly connected to a second rotary element of the third planetarygear device. The six shifting elements may include first to fourthclutches and first and second brakes. The first clutch may be disposedbetween the first rotary shaft and the second rotary shaft. The secondclutch may be disposed between the second rotary shaft and the fourthrotary shaft. The third clutch may be disposed between the first rotaryshaft and the fifth rotary shaft. The fourth clutch may be disposedbetween the seventh rotary shaft and the eighth rotary shaft. The firstbrake may be disposed between the second rotary shaft and a transmissioncase, and the second brake may be disposed between the sixth rotaryshaft and the transmission case.

According to the present disclosure, as set forth above, the multi-stagetransmission for a vehicle can realize at least nine forward shiftingstages and one reverse shifting stage with a relatively small number ofparts and a configuration such that the engine may be operated atdesired operation points, thereby maximizing an improvement in the fuelefficiency of the vehicle, and the engine may be operated more quietly,thereby improving the quietness of the vehicle.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure

DRAWINGS

In order that the disclosure may be well understood, there will now bedescribed various forms thereof, given by way of example, referencebeing made to the accompanying drawings, in which:

FIG. 1 is a diagram illustrating the configuration of a multi-stagetransmission for a vehicle according to one form of the presentdisclosure;

FIG. 2 illustrates an operation mode table of the transmission shown inFIG. 1;

FIG. 3 is a diagram illustrating the configuration of a multi-stagetransmission for a vehicle according to another form of the presentdisclosure; and

FIG. 4 illustrates an operation mode table of the transmission shown inFIG. 3.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

A multi-stage transmission for a vehicle according to a first and secondexemplary embodiments of the present invention may commonly include aninput shaft “IN”; an output shaft “OUT”; a first to fourth planetarygear devices “PG1”, “PG2”, “PG3” and “PG4” disposed between the inputshaft “IN” and the output shaft “OUT” to transmit rotary force, each ofthe first to fourth planetary gear devices PG1, PG2, PG3 and PG4 hasthree rotary elements, and at least six shifting elements, e.g. clutchesCL1-CL6, connected to rotary elements of the first to fourth planetarygear devices PG1-PG4.

A first rotary element S1 of the first planetary gear device PG1 may beselectively fixed to a transmission case CS. A second rotary element C1of the first planetary gear device PG1 may stay connected to a thirdrotary element R2 of the second planetary gear device PG2. A thirdrotary element R1 of the first planetary gear device PG1 may be variablyconnected, (i.e., is selectively, intermittently connected) to a secondrotary element C2 of the second planetary gear device PG2 and staysconnected to a first rotary element S3 of the third planetary geardevice PG3 and a first rotary element S4 of the fourth planetary geardevice PG4.

A first rotary element S2 of the second planetary gear device PG2 may bevariably connected to the input shaft IN, and the second rotary elementC2 of the second planetary gear device PG2 may be installed to beselectively fixable by one shifting element of the at least six shiftingelements and variably connected to the input shaft IN.

A second rotary element C3 of the third planetary gear device PG3 maystay connected to the output shaft OUT, and a third rotary element R3 ofthe third planetary gear device PG3 may be installed to be selectivelyfixable by another shifting element of the at least six shiftingelements.

A second rotary element C4 of the fourth planetary gear device PG4 maybe configured to be selectively connected to the input shaft IN, and athird rotary element R4 of the fourth planetary gear device PG4 may beconfigured to secure a state at least even temporarily connected to theoutput shaft OUT.

The first planetary gear device PG1, the second planetary gear devicePG2, the third planetary gear device PG3 and the fourth planetary geardevice PG4 may be sequentially arranged along the axial direction of theinput shaft IN and the output shaft OUT.

The second rotary element C2 of the second planetary gear device PG2 maybe installed to be selectively fixable to a transmission case CS bymeans of a first brake B1 from among the at least six shifting elements.The third rotary element R3 of the third planetary gear device PG3 maybe installed to be selectively fixable to the transmission case CS bymeans of a second brake B2 from among the at least six shiftingelements.

Therefore, the first brake B1 and the second brake B2 function asbrakes, respectively, such that the second rotary element C2 of thesecond planetary gear device PG2 and the third rotary element R3 of thethird planetary gear device PG3 may be in a rotatable state, or in arestrained state, not able to rotate by means of the operations of thefirst brake B1 and the second brake B2, respectively.

The other shifting elements from among the at least six shiftingelements may be configured to constitute variable connection structuresbetween the rotary elements of the planetary gear devices and betweenthe rotary elements of the planetary gear devices and the input shaftIN.

The configurations described above form the common configurations of thefirst form and the second form. In the first form shown in FIG. 1, thesecond rotary element C4 of the fourth planetary gear device PG4 may bevariably connected to the input shaft IN by still another of the atleast six shifting elements, and the third rotary element R4 of thefourth planetary gear device PG4 may stay connected to the output shaftOUT.

That is, the first clutch CL1 from among the at least six shiftingelements may form a variable connection structure between the secondrotary element C2 of the second planetary gear device PG2 and the inputshaft IN. The second clutch CL2 from among the at least six shiftingelements may form a variable connection structure between the thirdrotary element R1 of the first planetary gear device PG1 and the secondrotary element C2 of the second planetary gear device PG2. The thirdclutch CL3 from among the at least six shifting elements may form avariable connection structure between the first rotary element S2 of thesecond planetary gear device PG2 and the input shaft IN. The fourthclutch CL4 from among the at least six shifting elements may form avariable connection structure between the second rotary element C4 ofthe fourth planetary gear device PG4 and the input shaft IN.

Meanwhile, in the second exemplary embodiment shown in FIG. 3, thesecond rotary element C4 of the fourth planetary gear device PG4 maystay connected to the input shaft IN, and the third rotary element R4 ofthe fourth planetary gear device PG4 may be variably connected to theoutput shaft OUT by still another shifting element of the at least sixshifting elements.

That is, the first clutch CL1 from among the at least six shiftingelements may form a variable connection structure between the secondrotary element C2 of the second planetary gear device PG2 and the inputshaft IN. The second clutch CL2 from among the at least six shiftingelements may form a variable connection structure between the thirdrotary element R1 of the first planetary gear device PG1 and the secondrotary element C2 of the second planetary gear device PG2. The thirdclutch CL3 from among the at least six shifting elements may form avariable connection structure between the first rotary element S2 of thesecond planetary gear device PG2 and the input shaft IN. The fourthclutch CL4 from among the at least six shifting elements may form avariable connection structure between the second rotary element C3 ofthe third planetary gear device PG3 and the third rotary element R4 ofthe fourth planetary gear device PG4. As a result, the third rotaryelement R4 of the fourth planetary gear device PG4 is to be variablyconnected to the output shaft OUT.

In the first and second exemplary embodiments, the first rotary elementS1, the second rotary element C1 and the third rotary element R1 of thefirst planetary gear device PG1 are a first sun gear, a first carrierand a first ring gear, respectively. The first rotary element S2, thesecond rotary element C2 and the third rotary element R2 of the secondplanetary gear device PG2 are a second sun gear, a second carrier and asecond ring gear, respectively. The first rotary element S3, the secondrotary element C3 and the third rotary element R3 of the third planetarygear device PG3 are a third sun gear, a third carrier and a third ringgear, respectively. The first rotary element S4, the second rotaryelement C4 and the third rotary element R4 of the fourth planetary geardevice PG4 are a fourth sun gear, a fourth carrier and a fourth ringgear, respectively.

The forms of the transmission configured as above may also be presentedas follows. Specifically, the multi-stage transmission for a vehicleaccording to the one form of the present disclosure may include thefirst to fourth planetary gear devices PG1, PG2, PG3, and PG4 eachhaving three rotary elements, the six shifting elements configured tovariably provide frictional force, and the eight rotary shafts connectedto the rotary elements of the first to fourth planetary gear devices.

Hence, from among the eight rotary shafts, the first rotary shaft RS1may be the input shaft IN. The second rotary shaft RS2 may be directlyconnected to the second rotary element C2 of the second planetary geardevice PG2. The third rotary shaft RS3 may be directly connected to thesecond rotary element C1 of the first planetary gear device PG1 and thethird rotary element R2 of the second planetary gear device PG2. Thefourth rotary shaft RS4 may be directly connected to the third rotaryelement R1 of the first planetary gear device PG1, the first rotaryelement S3 of the third planetary gear device PG3 and the first rotaryelement S4 of the fourth planetary gear device PG4. The fifth rotaryshaft RS5 may be directly connected to the first rotary element S2 ofthe second planetary gear device PG2. The sixth rotary shaft RS6 may bedirectly connected to the third rotary element R3 of the third planetarygear device PG3. The seventh rotary shaft RS7 may be directly connectedto the second rotary element C4 of the fourth planetary gear device PG4.The eighth rotary shaft RS8 may be the output shaft OUT directlyconnected to the second rotary element C3 of the third planetary geardevice PG3 and the third rotary element R4 of the fourth planetary geardevice PG4.

In addition, from among the six shifting elements, the first clutch CL1may be disposed between the first rotary shaft RS1 and the second rotaryshaft RS2. The second clutch CL2 may be disposed between the secondrotary shaft RS2 and the fourth rotary shaft RS4. The third clutch CL3may be disposed between the first rotary shaft RS1 and the fifth rotaryshaft RS5. The fourth clutch CL4 may be disposed between the firstrotary shaft RS1 and the seventh rotary shaft RS7. The first brake B1may be disposed between the second rotary shaft RS2 and the transmissioncase CS. The second brake B2 may be disposed between the sixth rotaryshaft RS6 and the transmission case CS.

Meanwhile, the multi-stage transmission for a vehicle according to thesecond form of the present disclosure may include the first to fourthplanetary gear devices PG1, PG2, PG3, and PG4 each have three rotaryelements; the six shifting elements configured to variably providefrictional force, and the eight rotary shafts connected to the rotaryelements of the first to fourth planetary gear devices.

Hence, from among the eight rotary shafts, the first rotary shaft RS1may be the input shaft IN. The second rotary shaft RS2 may be directlyconnected to the second rotary element C2 of the second planetary geardevice PG2. The third rotary shaft RS3 may be directly connected to thesecond rotary element C1 of the first planetary gear device PG1 and thethird rotary element R2 of the second planetary gear device PG2. Thefourth rotary shaft RS4 may be directly connected to the third rotaryelement R1 of the first planetary gear device PG1, the first rotaryelement S3 of the third planetary gear device PG3 and the first rotaryelement S4 of the fourth planetary gear device PG4. The fifth rotaryshaft RS5 may be directly connected to the first rotary element S2 ofthe second planetary gear device PG2. The sixth rotary shaft RS6 may bedirectly connected to the third rotary element R3 of the third planetarygear device PG3. The seventh rotary shaft RS7 may be directly connectedto the third rotary element R4 of the fourth planetary gear device PG4.The eighth rotary shaft RS8 may be the output shaft OUT directlyconnected to the second rotary element C3 of the third planetary geardevice PG3.

In addition, from among the six shifting elements, the first clutch CL1may be disposed between the first rotary shaft RS1 and the second rotaryshaft RS2. The second clutch CL2 may be disposed between the secondrotary shaft RS2 and the fourth rotary shaft RS4. The third clutch CL3may be disposed between the first rotary shaft RS1 and the fifth rotaryshaft RS5. The fourth clutch CL4 may be disposed between the seventhrotary shaft RS7 and the eighth rotary shaft RS8. The first brake B1 maybe disposed between the second rotary shaft RS2 and the transmissioncase CS. The second brake B2 may be disposed between the sixth rotaryshaft RS6 and the transmission case CS.

As set forth above, the multi-stage transmission for a vehicle accordingto the present disclosure includes the four planetary gear devices PG1,PG2, PG3, PG4 and the six shifting elements configured to form nineforward shifting stages and one reverse shifting stage according to theoperation mode table, as illustrated in FIG. 2 and FIG. 4, respectively.Since the multi-stage transmission is configured to form nine shiftingstages and the high gear efficiency of a planetary gear for eachshifting stage can reach 98.8% a relatively small number of parts and asimple configuration, the multi-stage transmission for a vehicle cancontribute to the improved fuel efficiency and quietness of a vehicle,thereby ultimately improving the marketability of the vehicle.

Forms described may be changed or modified by those skilled in the artto which the present disclosure pertains without departing from thescope of the present disclosure, and various alterations andmodifications are possible within the technical spirit of the presentdisclosure and the equivalent scope of the claims which will bedescribed below.

What is claimed is:
 1. A multi-stage transmission for a vehicle,comprising: an input shaft; an output shaft; a first, second, third, andfourth planetary gear devices disposed between the input shaft and theoutput shaft to transmit rotary force, each of the first, second, thirdand fourth planetary gear devices having three rotary elements; and atleast six shifting elements connected to the rotary elements of theplanetary gear devices, the at least six shifting elements includingfirst, second, third, fourth, fifth and sixth shifting elements; whereina first rotary element of the first planetary gear device is fixed, asecond rotary element of the first planetary gear device stays connectedto a third rotary element of the second planetary gear device, and athird rotary element of the first planetary gear device is variablyconnected to a second rotary element of the second planetary gear deviceand stays connected to a first rotary element of the third planetarygear device and a first rotary element of the fourth planetary geardevice; wherein a first rotary element of the second planetary geardevice is variably connected to the input shaft, and the second rotaryelement of the second planetary gear device is installed to beselectively fixable by the fifth shifting element of the at least sixshifting elements and variably connected to the input shaft; wherein asecond rotary element of the third planetary gear device stays connectedto the output shaft, and a third rotary element of the third planetarygear device is installed to be selectively fixable by the sixth shiftingelement of the at least six shifting elements; wherein a second rotaryelement of the fourth planetary gear device is variably connected to theinput shaft by the fourth shifting element, and a third rotary elementof the fourth planetary gear device stays connected to the output shaft.2. The multi-stage transmission according to claim 1, wherein the firstplanetary gear device, the second planetary gear device, the thirdplanetary gear device and the fourth planetary gear device aresequentially arranged along an axial direction of the input shaft andthe output shaft.
 3. The multi-stage transmission according to claim 2,wherein: the second rotary element of the second planetary gear deviceis installed to be selectively fixable to a transmission case by thefifth shifting element, the fifth shifting element being a first brake,the third rotary element of the third planetary gear device is installedto be selectively fixable to the transmission case by the sixth shiftingelement, the sixth shifting element being a second brake, and the othershifting elements of the at least six shifting elements are configuredto constitute variable connection structures between the rotary elementsof the planetary gear devices and between the rotary elements of theplanetary gear devices and the input shaft.
 4. The multi-stagetransmission according to claim 3, wherein: the first shifting elementis a first clutch configured to form a variable connection structurebetween the second rotary element of the second planetary gear deviceand the input shaft, the second shifting element is a second clutchconfigured to form a variable connection structure between the thirdrotary element of the first planetary gear device and the second rotaryelement of the second planetary gear device, the third shifting elementis a third clutch configured to form a variable connection structurebetween the first rotary element of the second planetary gear device andthe input shaft, and the fourth shifting element is a fourth clutchconfigured to form a variable connection structure between the secondrotary element of the fourth planetary gear device and the input shaft.5. A multi-stage transmission for a vehicle comprising: a first, second,third, and fourth planetary gear devices having three rotary elements,respectively; six shifting elements configured to variably providefrictional force; and a first, second, third, fourth, fifth, sixth,seventh and eighth rotary shafts connected to the rotary elements of thefirst, second, third and fourth planetary gear devices, wherein thefirst rotary shaft is an input shaft, the second rotary shaft isconnected to a second rotary element of the second planetary geardevice, the third rotary shaft is connected to a second rotary elementof the first planetary gear device and a third rotary element of thesecond planetary gear device, the fourth rotary shaft is connected to athird rotary element of the first planetary gear device, a first rotaryelement of the third planetary gear device and a first rotary element ofthe fourth planetary gear device, the fifth rotary shaft is connected toa first rotary element of the second planetary gear device, the sixthrotary shaft is connected to a third rotary element of the thirdplanetary gear device, the seventh rotary shaft is directly connected toa second rotary element of the fourth planetary gear device, and theeighth rotary shaft is an output shaft directly connected to a secondrotary element of the third planetary gear device and a third rotaryelement of the fourth planetary gear device; and wherein the sixshifting elements include a first to fourth clutches and a first andsecond brakes, the first clutch is disposed between the first rotaryshaft and the second rotary shaft, the second clutch is disposed betweenthe second rotary shaft and the fourth rotary shaft, the third clutch isdisposed between the first rotary shaft and the fifth rotary shaft, thefourth clutch is disposed between the first rotary shaft and the seventhrotary shaft, the first brake is disposed between the second rotaryshaft and a transmission case, and the second brake is disposed betweenthe sixth rotary shaft and the transmission case.
 6. The multi-stagetransmission according to claim 5, wherein the first planetary geardevice, the second planetary gear device, the third planetary geardevice and the fourth planetary gear device are sequentially arrangedalong an axial direction of the input shaft and the output shaft.
 7. Themulti-stage transmission according to claim 5, wherein: a first clutchfrom among the at least six shifting elements forms a variableconnection structure between the second rotary element of the secondplanetary gear device and the input shaft, a second clutch from amongthe at least six shifting elements forms a variable connection structurebetween the third rotary element of the first planetary gear device andthe second rotary element of the second planetary gear device, a thirdclutch from among the at least six shifting elements forms a variableconnection structure between the first rotary element of the secondplanetary gear device and the input shaft, and a fourth clutch fromamong the at least six shifting elements forms a variable connectionstructure between the second rotary element of the fourth planetary geardevice and the input shaft.